1. Field of the Invention
The present invention relates to a lens barrel assembly having outer and inner barrels. More particularly, the present invention relates to a lens barrel assembly having outer and inner barrels and having a structure capable of preventing influence of water, droplets, dust or the like.
2. Description Related to the Prior Art
A lens barrel assembly or lens barrel is known in the field of cameras or optical instruments. An example of the lens barrel assembly is a zoom lens barrel of which a body can be extended or shortened. According to the movement, air pressure inside the lens barrel assembly is changed by a change in the inner volume. An cavity formed through the lens barrel assembly causes air to flow in and out.
If a cavity exists in the lens barrel assembly, droplets of water of dust may enter the lens barrel assembly, to mist lens elements or to damage electric parts. A closed state of the lens barrel assembly may be tightened for preventing such problems. However, air in the lens barrel assembly cannot be vented or cannot flow in and out smoothly, so zooming will not be carried out safely. There is a suggested camera in JP-A 9-197527 in which a vent with a waterproof structure is formed in each of the lens barrel assembly and a camera body, so as to cause air to flow into and out of the camera body.
JP-A 11-327018 discloses a camera in which the camera body has the vent, and an air permeable, water impermeable sheet is fitted on the vent on its outer side for the waterproof effect. A water shielding panel with pores is fitted on the vent on its inner side, the pores being smaller than the vent. Also, JP-U 3-062330 discloses a waterproof camera in which the lens barrel assembly is covered by bellows in a watertight manner, and air can flow in and out by opening a valve in the camera body in the course of extending or shortening the lens barrel assembly.
In JP-A 9-197527, the waterproof and dust resistant performance is obtained in the state with an interchangeable lens loaded on the camera body. However, no waterproof and dust resistant performance is obtained if the interchangeable lens is handled individually. Droplets or dust is likely to enter the lens barrel assembly when the interchangeable lens is changed in a bad condition as in a rainy weather, and directly manually in a construction site. In JP-A 11-327018 and JP-U 3-062330, there are disclosed ideas of waterproof and dust resistant performance. However, the camera body is inseparable with the camera body. There is no consideration of prevention of droplets or the like at the time of changing the interchangeable lens.